Rectifying system



Jan. 5, 1937. YOUNG 2,066,509

RECTIFYING SYSTEM Fild April 9, 1956 1/ /g w mm Patented Jan. 5, 1937 UNITED STATES PATENT OFFICE 8 Claims.

My invention relates generally to electrical systems and it has particular relation to rectifying systems.

It is desirable to provide a system whereby direct current may be obtained for a load circuit such as a group of street lights which are connected in series circuit relation and through which it is desired. that the current be kept at a substantially constant value regardless of the number of lamps in the circuit. Normally such a circuit will be of a relatively high voltage type, in which the amount of current flowing is relatively small. While the invention is particularly applicable to such a system, it will be understood that it may be applied to other types of load requiring direct current.

The object of my invention, generally stated, is to provide a rectifying system which shall be simple and efiicient in operation, and which may be readily and economically manufactured and installed.

The principal object of my invention is to provide for varying the impedance of an impedance device connected between a source of alternating current and a load circuit in such manner that a substantially uni-directional current is caused to flow in the load circuit.

An important object of my invention is to provide for changing the impedance of difierent parts of an alternating current circuit during successive half cycles of the alternating current in such manner that uni-directional current may be obtained therefrom.

Another important object of my invention is to provide for changing the impedance of different parts of an alternating current circuit during successive half cycles of the alternating current in accordance with a variable characteristic of the direct current power obtained therefrom.

A further object of my invention is to provide for controlling the conductivity of electric valves arranged to control the impedance in different parts of an alternating current circuit in such manner as to vary the amount of direct current power obtained therefrom.

A still further object of my invention is to provide for controlling the conductivity of electric valves arranged to control the impedance in different parts of an alternating current circuit in accordance with a variable characteristic of the direct current power obtained therefrom.

Other objects of my invention will in part be obvious and in part appear hereinafter.

My invention, accordingly, is disclosed in the embodiment hereof shown in the accompanying drawing, and it comprises'the features of construction, combination of elements and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the application of which will be indicated in the appended claims.

For a more complete understanding of the nature and scope of my invention, reference may be had to the following detailed description taken in connection with the accompanying drawing in which the single figure represents diagrammatically a concrete embodiment of my invention.

According to my invention, I have provided a main transformer for connection to a source of alternating current, the secondary winding of which is provided with a mid-tap. Across the terminals of the secondary winding, the series connected primary windings of a pair of imped- O ance devices are connected. The load circuit, which may comprise a series of street lights, is connected between the mid-tap of the secondary winding and the common connection between the primary windings of the impedance devices. In order to control the impedances of the impedance devices, a unidirectional current conducting device is connected across the secondary winding of each of these devices. Such a conducting device is preferably a hot cathode arc discharge 0 device, but it will be understood that other suitable rectifying devices may be employed. The conductivity of the uni-directional conducting devices is so controlled that the impedance of the respective impedance devices is changed during alternate half cycles. By properly selecting the half cycles during which the impedance of the impedance devices is lowered, a substantially uni-directional flow of current will take place through the load circuit. 0

In order to control the amount of direct current flowing in the load circuit, the uni-directional conducting devices are provided with control electrodes which may be energized from the alter- .ing in the load circuit will be maintained at a substantially constant value.

Referring now particularly to the single figure of the drawing, the reference character 10 designates, generally, a source of alternating current, such as a 60 cycle generator, which may be connected to energize the primary winding I i of a main transformer, shown generally at [2, having a secondary winding !3 provided with a midtap [4.

In order to convert the alternating current flowing in the secondary winding l3 into direct current, the primary windings l5 and 1B of a pair of impedance devices, shown generally at H and i8, are connected in series circuit relation across the terminals of the secondary winding 13. As illustrated, the impedance devices I7 and I8 are provided, respectively, with secondary windings l9 and 20. A load circuit, comprising a plurality of series connected street lights 2 l, is connected between the mid-tap M and the common connection 22 between the primary windings l5 and I6.

With a view to controlling the impedance of the impedance devices ll and [8, a. pair of electric valves, shown generally at 25 and 25, preferably of the hot cathode arc discharge type, is provided. Each of the valves 25 and 26 is provided, respectively, with an anode 25a and 29a, a control electrode 25g and 251, and a hot cathode 25c and 260. As shown, control electrodes 25g and 269 are connected through grid resistors 251* and 267' to secondary windings 2". and 28, respectively, of a grid transformer, shown generally at 23. It will be observed that the remaining terminal of each of the secondary windings 2'! and 28 is connected, respectively, to the cathode 25c and the cathode 280. The transformer 29 is provided with a primary winding which, as illustrated, is con nected for energization to a phase shifting circuit, shown generally at 35. The phase shifting circuit comprises a variable inductor 36 and a potentiometer 3? having an adjustable connection 38. The phase shifting circuit 35- is connected across the terminals 01 the secondary winding 39 of an auxiliary transformer, shown generally at 49, having a primary winding 45 which may be connected across the terminals of the alternating current source is. The primary winding 30 is connected between a mid-tap 42 on the secondary winding 39 and a common connection 43 between the inductor 36 and the potentiometer 3'1.

In order to automatically control the phase relationship of the voltage applied for energizing the control electrodes 25g and 25g, an armature 15 is provided for varying the inductance of the inductor 3B. The armature 43 forms a part of a regulator, shown generally at 4'1, which may be constructed in a manner similar to the construction of the regulator shown in my copending application, Serial No. 618,369, filed June 20, 1932. As shown, the armature 45 is connected to a lever arm 38 at the other end of which is an armature 49, the position of which is arranged to be controlled by means of a series winding 59 that, as illustrated, is connected in series circuit relation with the load circuit comprising the lamps 2|, and, therefore, the current flowing through it causes the position of the armature 49 to be changed in accordance with a variable characteristic of the load circuit, namely, the load current.

In operation, the movable connection 33 of the potentiometer Si is adjusted to the position corresponding to the amount of current it is desired to maintain in the load circuit. Variations in the current flowing through the load circuit will then, by means of the regulator 41, cause the time in each half cycle at which the valves 25 and 26 are rendered conducting to be advanced or retarded, so that correspondingly greater or lesser amounts of direct current will be caused to flow through the load circuit.

The electric valves 25 and 26 are so connected to the secondary windings l3 and 20, respectively, of the impedance devices that they function to decrease the impedance thereof during alternate half cycles of the alternating current. For example, consider the impedance device I! and the valve 25. Since the valve 25 is inherently disposed to conduct current only during half cycles of the same polarity, then, during these half cycles, the impedance of the impedance device H is relatively low. As a result, a substantial amount of current is permitted to flow during these half cycles through the primary L winding [5 and into the load circuit comprising the lamps 2!. For the next succeeding half cycles, during which the valve 25 is inherently non-conducting, the impedance of the impedance device I! is relatively high, and, as a result, a

negligible amount of current flows through the primary winding IS. The impedance device l8 and the electric valve 26 function in like manner. However, they are so arranged that during the next half cycles after which the valve 25 has been rendered conducting, the valve 26 is rendered conducting. As described hereinbefore, during these half cycles the impedance of the impedance device l8 will be reduced to a minimum value with the result that there will be a substantial flow of current through the primary winding [6 and into the load circuit comprising the lamps 21. During the next succeedi g half cycles, due to the uni-directional conducting characteristic of the electric valve 26, no current will flow therethrough, and the impedance of the impedance device l8 will be materially increased. As a result of the combined action during successive half cycles of the alternating current of the impedance devices I! and 18, direct current will flow through the load circuit and the amount of it may be regulated with the regulator 47 by shifting the time in each half cycle at which the valves 25 and 26 are rendered conducting so that the load current will be maintained at a substantially constant value.

While my novel rectifying system has been illustrated and described in connection with a load circuit comprising a plurality of series connected street lights, it will be understood that it may be utilized for other purposes where it is desired to provide direct current. Therefore, since certain changes may be made in the foregoing construction and different embodiments of the invention may be made without departing from the scope thereof, it is intended that all matter set forth in the foregoing description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

What I claim is:

1. An electric system comprising, in combination, circuit means for connecting a load circuit to a source of alternating current, a transformer having a primary winding interposed in series circuit relation in said circuit means and a secondary winding, a uni-directional conducting electric valve connected across said secondary winding to permit the flow therethrough only of alternate half cycles of the alternating current whereby the impedance of said primary winding is decreased during said alternate half cycles to permit the flow of substantially uni-directional current in said load circuit, a control electrode in said valve, phase shift means disposed to be connected for energization to said alternating current source, and means for connecting said control electrode for energization to said phase shift means.

2. An electric system comprising, in combination, circuit means for connecting a load circuit to a source of alternating current, a transformer having a primary winding interposed in series circuit relation in said circuit means and a secondary winding, a uni-directional conducting electric valve connected across said secondary winding to permit the flow therethrough only of alternate half cycles of the alternating current whereby the impedance of said primary winding is decreased during said alternate half cycles to permit the flow of substantially uni-directional current in said load circuit, a control electrode in said valve, and means for controlling the time in said alternate half cycles at which said control electrode is energized in accordance with a variable characteristic of said load circuit.

3. An electric system comprising, in combination, circuit means for connecting a load circuit to a source of alternating current, a transformer having a primary winding interposed in series circuit relation in said circuit means and a secondary winding, a uni-directional conducting electric valve connected across said secondary winding to permit the flow therethrough only of alternate half cycles of the alternating current whereby the impedance of said primary winding is decreased during said alternate half cycles to permit the flow of substantially uni-directional current in said load circuit, a control electrode in said valve, adjustable phase shift means disposed to be connected for energization to said alternating current source, circuit means interconnecting said control electrode and said phase shift means, and regulating means controlled in accordance with a variable characteristic of said load circuit for adjusting said phase shift means to control the time in said alternate half cycles at which said control electrode is energized, thereby maintaining a substantially constant flow of uni-directional current in said load circuit.

4. An electric system comprising, in combination, circuit means for connecting one terminal of a load circuit to a connection substantially mid-way between the terminals of an alternating current source, a pair of impedance devices, each having a primary and a secondary winding, said primary windings being disposed to be connected in series circuit relation across said alternating current source and the common connection being connected to the other terminal of said load circuit, and uni-directional conducting means connected to each of said secondary windings to permit the flow therethrough only of alternate half cycles of the alternating current whereby the impedances of said primary windings are decreased during said alternate half cycles to permit the flow of direct current in said load circult.

5. An electric system comprising, in combination, circuit means for connecting one terminal of a load circuit to a connection substantially mid-way between the terminals of an alternating current source, a pair of impedance devices, each having a primary and a secondary winding, said primarywindings being disposed to be connected in series circuit relation across said alternating current source and the common connection being connected to the other terminal of said load circuit, a uni-directional conducting electric valve connected across each of said secondary windings to permit the flow therethrough only of alternate half cycles of the alternating current whereby the impedances of said primary windings are decreased during said alternate half cycles to permit the flow of direct current in said load circuit, a control electrode in each of said valves, and means for energizing said control electrodes in synchronism with the frequency of said alternating current source.

6. An electric system comprising, in combination, a circuit means for connecting one terminal of a load circuit to a connection substantially mid-way between the terminals of an alternating current source, a pair of impedance devices, each having a primary and a secondary winding, said primary windings being disposed to be connected in series circuit relation across said alternating current source and the common connection being connected to the other terminal of said load circuit, a uni-directional conducting electric valve connected across each of said secondary windings to permit the flow therethrough only of alternate half cycles of the alternating current whereby the impedances of said primary windings are decreased during said alternate half cycles to permit the flow of direct current in said load circuit, a control electrode in each of said valves, phase shift means disposed to be energizedfrom said alternating current source, and means for connecting said control electrodes for energization to said phase shift means.

7 An electric system comprising, in combination, circuit means for connecting one terminal of a load circuit to a connection substantially mid-way between the terminals of an alternating current source. a pair of impedance devices, each having a primary and a secondary winding, said primary windings being disposed to be connected in series circuit relation across said alternating current source and the common connection being connected to the other terminal of said load circuit, a uni-directional conducting electric valve connected across each of said secondary windings to permit the flow therethrough only of alternate half cycles of the alternating current whereby the impedances of said primary windings are decreased during said alternate half cycles to permit the flow of direct current in said load circuit, a control electrode in each of said valves, and means operable in accordance with a variable characteristic of said load circuit for controlling the time in said alternate half cycles at which said control electrodes are energized.

8. An electric system comprising, in combination, circuit means for connecting one terminal of a load circuit to a connection substantially mid-way between the terminals of an alternating current source, a pair of impedance devices, each having a primary and a secondary winding, said primary windings being disposed to be connected in series circuit relation across said alternating current source and the common connection being connected to the other terminal of said load circuit, a uni-directional conducting electric valve connected across each of said secondary windings to permit the flow therethrough only of alternate half cycles of the alternating current whereby the impedances of said primary windings are decreased during said alternate half cycles to per- 7 with a variable characteristic of said load circuit for adjusting said phase shift means to control the time in said alternate half cycles at which said control electrodes are energized, thereby maintaining a substantially constant flow of 5 uni-directional current in said load circuit.

HUGH E. YOUNG. 

